The present invention relates to a safety device for use in a centrifugal separator in which sedimentation tubes or capillary tubes may be mounted for centrifugal separation of substances contained therein, the safety device being effective in preventing the centrifugal separator with the sedimentation tubes mounted from rotating at the high speed of rotation required for centrifugal separation in the capillary tubes.
There has been put to use a centrifugal separator having two selective modes of operation: In one mode, sedimentation tubes with blood samples contained therein are mounted on a rotor for centrifugal separation of the blood samples; and in the other mode, blood samples are placed in capillary tubes that are mounted on the rotor and subjected to centrifugal separation for hematocrit determination.
The rotor of the centrifugal separator is normally rotated at about 12,000 rpm for hematocrit measurements, and at about 4,000 to 5,000 rpm for blood sample separation. For such blood sample separation with sedimentation tubes mounted in the centrifugal separator, the operator manipulates a selector switch on the control panel to select low-speed rotation for driving the rotor to rotate substantially at the speed ranging from 4,000 to 5,000 rpm. When hematocrit determination is to be made with capillary tubes mounted in the centrifugal separator, the operator shifts the selector switch to select high-speed rotation for rotating the rotor approximately at the high-speed of 12,000 rpm. This manual control however has a tendency for erroneous switching operation. In particular, when the operator shifts the selector switch to the high-speed side in error with the sedimentation tubes mounted for blood sample separation, the rotor is caused to rotate at 12,000 rpm, with the result that sedimentation tube containers are subjected to intensive centrifugal forces, and the containers or the sedimentation tubes may be broken or otherwise damaged.